Electrical heating element.



E. H. BUCKLE.

ELECTRICAL HEATING ELEMENT.

APPLICATION FILED DEC. 23, 1914.

Patented Dec. 28, 1915.

2 SHEETS-SHEET I.

INVENTOR.

WITNESSES:

Patented Dec. 28, 1915.

2 SHEETS4SHEET 2.

RS@ L/2 Www @l i NVENTOR. Mam/IAL JV' m A TTORNE 1 E. H. RUCKLE.

ELECTRCAL HEATING ELEMENT.

APPLICATION FILED DEC. 23. 1914.

EDWARD H. BUCKLE, 0F CHICAGO, ILLINOIS.

ASSIGNOR TO HUGHES ELECTRIC HEAT- ING COMPANY, CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTRICAL HEATING- ELEMENT.

Specification of Letters Patent.

Patented Dec. 28, 1915.

Application led December 23, 1914. Sera1No.878,656.

To au w/iom t may concern:

Be it .known that I, EDWARD H. BUCKLE, a citizen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvementsin Electrical Heating Elements, of which the following is a specification. 4 l

My invention relates to electrical heatingv elements and covers improved construction and arrangement which will make such devices more ei'iicient.

The invention concerns particularly heating elements to be used in bake ovens, broil-` ing ovens, toasteis and the like. Such elements usually comprise a supporting frame on which a heating wire or coil passes back and forth to give thedesired heating capac ity and various means have been provided for supporting the wire and insulating sections thereof from each other.

One of the important objects of my in vention is to provide improved supporting and insulating construction and arrangement for the heating wire sections. My improved supporting means are in the form. of holders or frames in which pockets are provided for securely holding and retaining bushings of suitable insulating material through which the heating wire passes, the construction and arrangement being such that even though the bushings should crack or break they would still be retained within their supporting frames and insulating of the heating wire is assured.

Another object of the invention is to provide improved arrangement particularly adaptable for oven heating units, the arrangement involving improved means for preventing concentration of heat at the center of the heating element and for effecting lateral and upward flow of the generated heat to be deflected by the oven walls downwardly against. the material to :be baked, my improved construction eliminating the necessity of heat bathing or directing mechanism or parts;

Another object is -to provide' simple and efficient construction o the element as a whole and of the various wire holding and other parts thereof in order provide a strong and efficient yet inexpensive element.

In the v drawings which show various adaptations of my invention Figure `1 is a.

plan view or an oven heating element with part of the top thereof broken away; Fig. 2 1s a side view; Fig. 3 is a sectional view on plane 3-3, Fig. l; Fig. 4 is an enlarged side elevational view of one of the heating wire supporting structures; Fig. 5 is a side elevational view of one form of'insulating bushing that may be used with the frames; Fig. 6 is a sectional view on plane 6-6, Fig. 4; Fig. 7 is a similar sectional view but showinga different form of bushing; Fig. 8 is a similar sectional view showing the same forni of bushing as Fig. 7 but showing a modified form of frame; Fig. 9 is a similar sectional view as Fig. 6 but showing a different form of supporting frame sti-ucture; Fig. l0 is a view of the under side of a broiler oven heating element; Fig'. il is a sectional view on plane llll, Fig. l0; Fig. 12 is a plan view of a iractioii'oi` a toaster element showing modified arrangement for supporting the heating wire supporting strips or frames; Fig. i3 is an end view of one of the wire supporting frames' shown in Fig. l2; and i4 is an end view of a modified form oir' wire supporting frame. n

Referring to Figs. I to 5, the oven heating element comprises a base l preeraby formed of .sheet metal with the side and end edge sections 2 and 3 bent upwardly to stiiien and strengthen the base. Extending inwardly a distance from the sides and ends of-y the base and secured thereto in vertical position are frames 4 for supporting the heating wire circuits of which two, 5 and 5', are shown. The frames 4 at the corners of the b ase extend diagonally as indicated, and at one end of the base a' section of the sheet metal of which the base is formed is prolonged upwardlyl to forni a wall 6 for supporting the circuit terminals 7 8 and 9, these terminals being of any suitable construction, comprising as shown the screws a secured to the wall by suitable nuts b, the screws and the nuts being insulated from the wall by suitable insulating washers d and e.

The construction of the wire supporting members is best shown in Figs. 4, 5 and 6. The members there shown each comprise the vertical upright sections 7 and g which abut against each other, and the horizontal base or llange sections la and z'. The

gag,

upright sections f and g have the registering openings y' and 7c therein, the edge sections m and n of which are deflected outwardly to an angle in order to `produce the annular ll-shaped pocket o. ing bushing 10 shown in Figs. 4, 5 and 6 comprises the central section p whose annular surface is V-shaped to snugly fit in the pocket 0 of the supporting frame and extending in opposite directions from the central sections 79 are the cylindrical ends g and g', these ends being ot a length to eX- tend a distance beyond the deliected edges j and 7c of the support. Each trame is rst stamped from sheet metal, the holes 70 and y' with their deflected edge sections being formed during 4the stamping operation. Either during or after the stamping operation the flanges k and z' are formed, but before bending the stamping to form the upright sections f and g the bushing or bushings are inserted intothe hole or holes of one let' the sections and the blank then bent along a median line and the other section thus formed brought against the first section and receiving in its holes the corresponding ends of the bushings. After completion of the trame the bushings will be securely clamped and locked in position. Each bushing has a longitudinal passagewayfr' through which a heating Wire or spiral may pass. r1`he trames may be secured in any desired manner to the base 1. Preferably they are secured by spot Welding their flanges k and to the base as indicated at 11.. 1n the diagonally extending corner trames 41 the bushings are spaced farther apart than in the other trames in order that the wires passing therethrough may retain parallelism.

1n the arrangement shown in Fig. 1, the `wire for circuit 5- starts from terminal 7 and passes then through the outer bushing oi2 the frame ia which extendsvinwardly from the end ot' the wall 6, the wire then passing adjacent the louter edge of the base through the outer bushings of the various supporting trames and passes eventually through the outer bushing ot the trame 1b extending from the other end or the Wall 6, and being secured then to the terminal 9'. rthe conductor for the circuit 5 extends Afrom the terminal 8 through the inner bushing of trame au, then parallelly with` the outer conductor 5 through the inner bushings of the supporting frames and finally through the inner bushing of frame 1b to terminal 9. Suitable switch mechanism, (not shown) will in practice be connected with the current supply circuit leading to the terminals for effecting separate or parallel or serial connection of the heating circuits 5 and 5 with the main circuit. r1`he heating conductors are protected by a cover 12 which is preferably stamped from sheet The insulat-l meager metal and made rigid and strong by deiecting its side and end edge sections 13 and 14 downwardly, the cover resting on the tops of the conductor supporting frames. 1n order to also protect the terminals the section 15 integral with the cover projects frpm the end thereof to overhang the ter'- minals.

r1`he opposed stiffening edges of the base and cover do not meet but are short in order to leave the side and end outlets 16 and 17 for the `generated heat. The element is placed in the bottom of a baking oven and the banking utensils may be set right on top of the element or on grids placed in the oven over the'element, the heat issuing .from the outlets 16 and 17 liowing upwardly and being deflected by the oven walls down- Wardly against the material' to be baked. 1t has been found necessary, to e'ect efficient baking, to prevent concentration of heat at the center of the'element, that is, to prevent excessive upward radiation of heat from the central part of the element to the under side of the baking utensils. 1n prior arrangements' special baffle plates or structures were placed over the heating element to laterally deflect away such excessive heat. 1n my arrangement such heat concentration at the center of. the element is efficiently prevented by a rectangular frame or box 18 interposed between the base and cover of the element. rThis frame is preterably stamped integral of sheet metal and is secured to the base by being spot welded thereto. rThe frame 18 is preferably the same height as the heating conductor supporting members 4 so that the cover 12 will rest intimately against the top thereof, and this frame together with the inclosed air space will then form an etiicient barrier or insulator against the inward flow and concentration of heat generated by the heating conductors, and the generated heat must therefore flow laterally through the outlets 16 and 17 to be carried upwardly and be deflected against the top of the baking utensils, only suiiicient heat being radiated di-A rectly upwardly from the central section of the element to effect efiicient baking together with the heat deflected downwardly. 1n the cover 12, insulating frame 18, and base 1 are the holes 19, 20 and 21 respectively through which screws 22 may pass to thread in the oven bottom or in a suitable support provided inthe oven for the element, these bolts besides securing the element in place in the oven also securing the cover in place. @ther means could of course be provided for holding the cover in place on the element or for securing the element in the oven.

yFigs. 7, 8 and 9 show modiied heating conductor supporting structures. 1n Fig. 7 the bushing shown has the cylindrical central section pa instead ot' the conical form shown in Fig. 5, and the metal sections adjacent the holes for receiving the cylindrical ends of the bushing are deflected to snugly fit the cylindrical section as shown. in Fig. 8 thebushing is the same as shown in Fig. 7 but the supporting frame upright sections ,t and g instead of being brought entirely together are left spaced apart a distance equal to the width of the cylindrical bushing section pa. In the arrangement of ig. 9 the supporting frame, instead of being an 'integral piece of sheet metal. is formed by two separate side members e and t provided with the base flanges u and o respectively, and any type of bushing can be inserted between the plates. As shown, the arrangement with reference to the bushing is the saine as in Fig. 6.

.ln l@ and ll a broiler heating elenient is shown. The supporting frame for this element is in the form of a shallow, inverted, sheet metal container 23. Extending crosswise of this container isa suitable number of frames or bands 24 for supporting the sections of heating conductors 25 and 26. The supporting frames may be of any of the constructions shown in Figs. 1 to 9 and are secured to the top 23a by spot welding their flanges it and e thereto, or in any other suitable manner, the vertical sections of the frames supporting bushings 27 through which the heating conductors pass. 0n the end wall 23b -suitable terminals 28, 29 and 30 are grouped with which the heating conductors connect. Conductors 2:2 and '26 connect with 'terminals 28 and 29 respectively and then pass back and forth in parallel relation through the bushings of the frames 2li and eventually `both connect with terminal 30. To guide the conductors to the frames short longitudinally extending frames 2.0i@ and 24th are secured adjacent the terminals, and to keep the conductors properly spaced at the turns short transverse frames 2Q, 24d and 24e are provided as shown in Fig. l0. The heating element 23 is secured with its top 23a against the top of the oven and the generated heat is deflected. downwardly. By suitable switch mechanism controlling the flow of supply current the heating conductors can be connected individually or in series or parallel arrangement with the supply circuit.

In Fig. l2 a heating element is shown adapted for toasting purposes. In the con'- struction shown a row of heating conductor supporting frames 3l are set transversely between the sides of a shallow container or frame 32, these frames supporting rows of alined bushings 33 through which a heating conductor 34 is threaded back and forth with its ends secured to suitable terminals 35 mounted on the end wall 32E, only one of such terminals being shown. The frames 3l could be of any of the constructions shown 'of the bushings.

in Figs. 1 tol1 and secured to the floor of the container by having their flanges spot welded thereto. However, it may be desirable to have these supporting bands or strips readily detachable. The structure may therefore be as shown in Fig. 13, this being substantially the same structure as shown in Figs. l and 6 but with the anges omitted from the end members f and g which are brought intimately together after insertion These strips-can then be slipped into suitable U-shaped guides 36 secured to the side walls of the container 32, these guides keeping the sections 7 and g of the frames together. Additional means may be provided for keeping the sections and g together by bending the end w of one of the sections around the edge of the other as shown in Fig. le.

It is evident that the heating conductor arrangement in the toaster element could be he same as that in the broiler element. In other words, the structure shown in Fig. l0 could be used in an oven for broiling or could be inverted and be used outside the oven for toasting, and the structure of Fig. l2 could be inserted into a broiling unit.

The various constructions and. arrangements I have shown and described have been found to be very efficient. The sheet metal construction gives strength and rigidity. The heating conductor supporting. frames or strips are particularly efficient. The bushings which may be of porcelain or any other suitable insulating material are always rigidly held in place and cannot fall out even though they should crack, eiiicient insu lation being always thus assured. The mannelJ of inserting the bushings in the frames during formation lof the frames is unique and very elicient.

I do not of course desire. to be limited to the precise constructions and arrangements herein shown, described and referred to as modifications are no doubt possible which woul still come within the scope of the i11- vention.

l.' claim as follows:

l. In an electrical heating element, the combination of a supporting base, heating conductorsrsupported on said base adjacent the outer edge thereof, a top over said base separated therefrom a distance to leave lateral outlets for the heat generated by said conductors, and walls extending between said base and cover for forming a heat insulating space at the middle section of said element for preventing concentration` of' generated heat at said middle section.

2. in an electrical heating element, the combination of a supporting base, holder members extending inwardly a distance from the edges of said base, heating conductors passing through said holders, a top spaced from said base to leave lateral outniemeer iet for beat generated by 4salici conductors, my name this :21st (tay of December, D..

and Wll extending between th? base anni 19d/L top an a jacent the inner ends o said holders to form a heat insulating airspace at EDWARD H' BUCKLE 5 the central section of the element .for pre- Witnesses:

-renting concentration of heat thereat. C. J. SCHMIDT,

1n witness whereof, l hereunto subscribe EDMUND G.. NGERSOLL. 

